Determination of remaining useful life of gas turbine blade

a technology of gas turbine blades and useful life, which is applied in the direction of material analysis using wave/particle radiation, instruments, and static/dynamic balance measurement, etc., can solve the problems of turbine blades that fail at a much less stress than the turbine blade can withstand, damage growth on the vibration characteristics of turbine blades, and deterioration of turbine blades

US20070272018A1Inactive Publication Date: 2007-11-29HONEYWELL INT INC
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Patent Information

Authority / Receiving Office
US · United States
Patent Type
Applications(United States)
Current Assignee / Owner
Publication Date
2007-11-29
Estimated Expiration
Not applicable · inactive patent

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Abstract

A system may be used to indicate a need for replacement of a vibrating structure and includes a sensor, an indicator, and a processor. The sensor senses a frequency of vibration of the vibrating structure. The indicator is controlled to provide an indication of the need for replacement of the vibrating structure. The processor compares the frequency of vibration of the vibrating structure to data that relates the vibration frequency of the vibrating structure to fatigue damage of the vibrating structure, and controls the indicator based on the comparison.
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Description

TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to a method and / or system for the determination of the remaining useful life of a turbine blade such as a gas and / or a steam turbine blade.BACKGROUND OF THE INVENTION

[0002] Gas turbine blades are generally subjected to variable speeds and loading. The variable loading on the gas turbine blades are mainly caused by fluid jets impacting the gas turbine blades and the starting and shutting down of the gas turbine itself. This variable loading causes variable mean stresses and variable alternating stresses on the gas turbine blades. The variations of these stresses subjects the gas turbine blades to mechanical forces such as fatigue, creep, thermo mechanical fatigue, etc. Fatigue, for example, causes a turbine blade to fail at a stress that is much less than the turbine blade can withstand when it is new.

[0003] Many studies have attempted to deal with the problem of turbine blade failure. For example, some studies have at...

Examples

Embodiment Construction

[0017]Fatigue is a phenomenon in which repetitive loads cause a structure to fail at a stress level that is much lower than the stress level that the structure can withstand when it is new and unused. The principal contributing factors to fatigue failure are the number of load cycles experienced by the structure and the presence of local stress concentrations. Fatigue cracks result from plastic deformation, which in turn results from initiation and propagation of a crack. Low cycle fatigue is associated with large stresses causing considerable plastic deformation with failure cycles Nf in the range of 102 to 104.

[0018]The Table defines certain parameters, variables, and constants used in the analysis presented herein.

AArea of cross sectionbBreadth of beamDDamage variableD0Initial damageeOffsetEYoung's modulusE0Young's modulus for undamaged materialgacceleration due to gravityGShear modulushDepth of beamIxxmoment of inertia of beam cross section about xxaxisIyymoment of inertia of be...